Dipolar cycloaddtions of several mesoionic compounds with tert-butylfulvene derivatives; versatile reactions, sterically controlled [4π+ 6π] cycloadditions and a new route to heterocycles isoelectronic with azulene
Several mesoionic compounds react with 2-tert-butylfulvene derivatives to form [4 pi + 2 pi] and [4 pi + 6 pi] cycloadducts, which under the reaction conditions, undergo further fragmentation, elimination, or isomerization giving a variety of products including several condensed heterocycles which are isoelectronic with azulene.
Kato, Hiroshi; Kobayashi, Tomoshige; Tokue, Kazuhiko, Journal of the Chemical Society. Perkin transactions I, 1993, # 14, p. 1617 - 1620